Telegraph and telephone system



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TELEGRAPH AND TELEPHONE SYSTEM. No. 534,670. Patented Feb. 26, 1895-;

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TELEGRAPH AND TELEPHONE SYSTEM. No. 534,670. Patented Feb. 26, 1895.

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0. A. ROLPE. TELEGRAPH AND TELEPHONE SYSTEM.

Patented Feb. 261895..

E No. 534,6"70.

UNITED STATES PATENT @FFIfiE.

CHARLES A. ROLFE, OF CHICAGO, ILLINOIS.

TELEGRAPH AND TELEPHONE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 534,670, dated February 26, 1895.

- Application filed September 16, 1893. Serial No. 485,715. (No model.) I

.To all whom it may concern.-

Be it known that I, CHARLES A. ROLFE, a citizen of the United States, residing at Ohicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Telegraph and Telephone Systems, of which the following is a specification.

My invention relates to telegraph, telephone and analogous electric signal systems involving a neutral line arranged parallel with a closed metallic circuit, and employed in conjunction with the closed metallic circuit or main line for establishingacircuit between the main or central ofiice and a substation. In thus employing a neutral or parallel line as a means for avoiding disturbances while talking over a circuit involving both lines, as aforesaid, the effectiveness of the neutral line 1s not uniform, and it will be found to vary with difierent days. I have also discovered that on some days I can secure the best results by using the right of the neutral line while on other days the best results can be secured by utilizing the left of the neutral line, and hence that on some daysI find it advantageous to connect up one end of a normally open neutral line, and on other days to connect up the opposite end thereof.

My invention may be attained by various arrangements of switch mechanisms and telephones as hereinafter set forth.

In the accompanying drawings,-Figure 1 is a diagrammatic representation of a system involving my invention and illustrating an arrangement whereby a telephone can be connected with the right of neutral and right of the main line or with the left of neutral and left of the main line, at will. Fig. 2 illustrates one of the switch levers. Fig. 3 isalike view illustrating an arrangement of two telephones at the main station whereby a like result can be attained. Fig. 4 is a like view illustrating an arrangement whereby the foregoing results can be attained, and also, whereby when desired, the right of neutral can be connected with the left of the main line, or the left of neutral be connected with the right of the main line, thereby securing a circuit whose resistance remains constantly inde closed metallic circuit having suitable nor mally open branches. The main or central office arrangement also comprises a telephone, illustrated by the transmitter O, the receiver 0 and a hook O for the receiver, and preferably this arrangement also includes a condenser E for purposes well known to those familiar with the art. In like manner the street or transmittingstation also comprises a telephone represented by the transmitter F, receiver F and hook F 'for the receiver, and

preferably a condenser G likewise provided for well known purposes.

The main signal line or circuit 1 is paralleled byan auxiliary or neutral line 2 having normally open ends and employed to neutral; ize efiects resulting from induction and tending to create disturbance during the transmission of voice currents between the stations.

As a matter of convenience, a three pivot.

switch H is provided at the street station and arranged to connect the telephone thereat, with the main line 1 at eitherside of the signal transmitting instrument, itbeingobserved that such connection is made through the switch when the receiver is ed the hook. The street station telephone also connects with the neutral wire, and where thecondenser G or analogous device is employed, the same can be placed in the branch between the telephone and the neutral wire, as illustrated.

The ends of the neutral line or wire are normally open, and can be alternately connected up with the main signal line, and main or central office telephone, by means of a loop switch D arranged at the main or central office. l

The loop switch D comprises a pair of switch too or contact levers D and D one of which is employed to connect the main or central office telephone with the right of the neutral line and right of the main line, while on the other hand, the remaining switch lever is employed to connect the said telephone with the left of the neutral line and left of the main line. To such end therefore, the telephone wire 3 is arranged to form a loop which includes a pair of contacts 4 allotted to the switch-lever D and a pair of contacts 5 allotted to the switch-lever D. The contacts 4 remain in electrical connection respectively with opposite sides of the switch-lever D which latter is constructed with metallic sides 6 insulated from one another by a suitable insulating material as at 7, and likewise, the contacts 5 remain in electrical connection respectively with opposite sides of the switch-lever D which is constructed like the lever D The loop switch also comprises a couple of contacts 8 respectively allotted to the right of main line and right of neutral line, and couple of like contacts 9 respectively allotted to the left of main line and left of neutral line. For such purpose, the end N. R. of the neutral right, connects with one of the contacts 8, while the right M. R. the main signal line, is connected with the remaining contact 8 by a branch 10. On the other hand the end N. L. of the neutral left, is connected with one of the contacts 9, while the left M. L. of the main signal line is connected with the remaining contact 9 by a branch 11. The contactsS and 9 are arranged with relation to the switch-levers, and the latter are so constructed, that by bringing lever D between and in engagement with the contacts 8 the latter will connect with the telephone loop through the medium of the sides of said lever and its allotted contacts 5, while on the other hand, by bringing lever D between and in engagement with the contacts 9, said contacts willconnect with the telephone loop through the sides of said lever D and its allotted contacts 4:. The lever D can therefore be adjusted so as to place the main or central office telephone in connection with the normally open end of the right portion of the neutral line, and corresponding right portion of the main line, and conversely the lever D can be adjusted so as to place such telephone in connection with the normally open end of the left portion of the neutral line and corresponding left portion of the main line. When the main or central oftlcetelephone is not in use, both ends of the neutral line are left open, and this can be done by throwing the switch levers out of connection with their respectively allotted contacts 8 and 9, it being observed that by way of illustrating the functions of the switch levers, I have in Fig. 1 shown one of thelevers in position to establish connection between contacts 5 and 8, and represented the remaining lever in position to break connection between the contacts 4 and 9. The construction of switch lever herein provided is best shown in Fig. 2, which represents the switch lever D it being understood that hoth switch-levers are constructed alike. particular construction of switch-lever shown, nor do I limit myself to the particular arrangementof switch-levers and contacts since the same can obviously be varied without departing from the spirit of my invention, which involves a switch suitable for changing the telephone circuit to either the right or left of the neutral line, at will. With further reference however to Fig. 1, the circuits for the various positions of switch D may be traced as follows, to wit: When the switch le ver D is adjusted so as to bring its metallic sides in contact with the contact points 8, 8, the main or central office telephone, will as aforesaid, be in connection with the right portion of the neutral line (2 N. R) and branch 10 of the right portion of the main line 1. The circuit will then be as follows, to wit: through the telephone apparatus at the main station, the telephone circuit 3, contact points 4 and 5, the opposite metallic sides of lever 61, the contacts points 8, the right portion of the main line including branch 10, the right portion of the neutral line (N. R), the wires connecting the main and neutral lines with the telephone apparatus at the sub station, and also through said telephone apparatus. 011 the other hand, when lever D is out of contact with contact points 8, and lever D is adjusted so as to bring its metallic sides in contact with the contact points 9, the circuitwill be as follows, to witz-through the telephone apparatus at the main station, the telephone circuit 3, the contact points 4 and 9, the metallic sides of lever D the left portion of the main line including branch 11, the left portion of the neutral line (N. L), the wires connecting the main and neutral lines with the telephone apparatus at the sub station, and also through said telephone apparatus.

In the system illustrated in Fig. 3, the same results are attained, the essential difference of arrangement being that I provide at the main station a couple of telephones H II respectively for connection with right and left branches 12 and 13 of the main line 1, and switches I and 1' respectively allotted to one and the other of said telephones and to one and the other of the normally open ends of the auxiliary or neutral line 2. With this explanation, the system illustrated by Fig. 3 will be readily understood by those skilled in the art, it being seen that the difference between Figs. and 1 consists essentially in the fact that in Fig. 1 the switch mechanism at the main station is centered in one apparatus with reference to one telephone whereby the single telephone can be connected with the right of neutral and right of the mainline in alternation with its connection with the left of neutral and left of the main line, while in Fig. 3, I provide a telephone apparatus with suitable switch mechanism for the right of I do not, however,limit myself to the IOC ,right of main and right of neutral.

neutral and right of the main line, and du plicate such arrangement for the left of neutral and left of main.

In the system illustratedin Fig. 4 all of the foregoing ends are attained by an arrangement similar to Fig. 1, and in addition thereto, the telephone at the main or central office or station may be connected with the right of neutral and left of main, or with the right of main and left of neutral, so that when desired, I can obtain a circuit whose resistance remains constantindependentof the point at which connection is made between the main line and the neutral line at a sub-station. This last mentioned result is attained by suitable switch mechanism illustrated by a four point switch mechanism. For example, the point 14 is for the right branch 15 of the main line, the point 16 is for the left branch 17 of the main line, the point 18 is for the right end of the neutral line, and the point 19 is for the left end of the neutral line. With such arrangement of points the two switch-levers 20 and 21 can be employed as follows, to wit: By connecting said levers re spectively with points or contacts 14 and 18 the telephone, L will be connected with the, By con necting said levers respectively with points 16and 19 the telephone L will be connected with the left of main and left of neutral. On the other hand however, the telephone can be connected with the right of neutral and left of main line by connecting the levers respectively with points 18 and 16, or the telephone can be connected with the left of neutral and right of main line by connecting one lever with point 19 and the other with point 14.

While therefore I can by each and all of the foregoing described arrangements obtain the shortest circuit between the central station and any station which is at less distance from the central office than half the length of the metallic signaling line or main line, I can by the arrangement last mentioned or described, connect the right of the neutral line with the left of the main line, or the converse of such and obtain a circuit whose resistance remains constant, independent of the point at which connection is made between the main line'and the neutral line at a substation for talking. This will be readily understood from the fact that the neutral line parallels the main line comprising a metallic circuit, and hence, when for example the right endof the neutral line is connected with the left of the main line a change of sub station selected for talking will lengthen the portion of one line used in the circuit proportionally to the shortening up of the portion of the other line used in such circuit.

In this specification, I desire to cover the matters common to all of the systems or arrangements illustrated, and to further cover the special system, illustrated in Fig. 4.

In my application, Serial No. 462,357, filed February 15, 1893,I have claimed the special switch shown in Figs. 1 and 2.

It is also understood that while my invention is particularly applicable to police telegraph signal systems, I can apply it to other analogous systems, and that in place of telephones, I may use writing machines or phonographs.

What I claim as my invention is- 1. The combination of a main line, a neutral line, and switching means for connecting up the right or left of the lines in circuit, substantially as described.

2. The combination of a main line, a neutral line, and switching means for connecting either side of one with either side of the other line, substantially as described.

3. The combination of the main line, neutral line, means for connecting the two lines at one or more substations and" telephones or the like at the main station arranged for connection respectively with the right and left of the lines, substantially as described;

4. The combination with a main line anda neutral line each having right and left portions, and a telephone for talking overa metallic circuit involving both lines, of a switch for changing such circuit at Will to either the right or left portions of the main and neutral line, substantially as described.

5. The combination with the main signal line and the neutral line in a system such as set forth, of a switch whereby the normally open ends of the neutral line can be alternately connected with the main line and main and central telephone, substantially as described.

6. In a system such as set forth, a normally closed main signal line, having normally open ICO branches and including transmitting and receiving instruments, an auxiliary or neutral line arranged parallel with the main line and having normally open ends, and switching mechanism for placing the right and left of both lines, alternately in circuit, substantially as described.

7. The combination with a normally closed metallic circuit including signal transmitting instruments and a signal receiving instru ment at a central station, of an auxiliary circuitor neutral line extending parallel with the said metallic circuit and normally open at the central office, one or more telephones adapted to be bridged between said metallic circuit and said auxiliary circuit at different stations, a telephone receiver at the central oflice, and a switch for connecting the receiver in a branch from said metallic signaling circuit to either terminal of said normally open auxiliary circuit, substantially as specified.

8. The combination with a normally complete signaling circuit including signal sending instruments at different substations and a signal receiving instrument at a central station, of an auxiliary circuit or neutral line extending parallel with said signaling circuit,

and normally open at the central station, current transmitting instruments at the different substations adapted to be connected between the said metallic signaling circuit and a portion of the auxiliary circuit extending to the central station, a receiving instrument adapted to respond to the transmitted current at the central station, and a switch adapted to connect the said signal receiving instrument in a branch between the metallic signaling circuit and either terminal of the said auxiliary circuit, substantially as described.

9. The combination with a normally continuous metallic signaling circuit including signal transmitting instruments at substations and a signal receiving instrument at a centraloffice, of an auxiliary circuit or neutral 

